Formation of oxo-centered trinuclear chromium carboxylate complexes and hydrolysis of Cr3 as established by paramagnetic 2H NMR spectroscopy

• Paramagnetic 2H NMR is used to follow reactions of chromium carboxylate assemblies.
• Formation of [Cr3O(O2CCD3)6(H2O)3]+ involves mononuclear & dinuclear intermediates.
• Cr3 hydrolysis reaches an equilibrium in water, blood plasma, & cell culture media.
• Cr3 degradation is more rapid in muscle homogenate.

Paramagnetic 2H NMR techniques have been utilized to study the mechanism of formation of the oxo-bridged trinuclear Cr(III) carboxylate assembly [Cr3O(O2CCD3)6(H2O)3]+ from [Cr(H2O)6]3 + and d4-acetic acid. These studies reveal a complex mechanism dominated by the involvement of dinuclear intermediates. The oxo-bridged trinuclear Cr(III) carboxylate assembly [Cr3O(O2CCH2CH3)6(H2O)3]+ has been suggested for use as a chromium nutritional supplement and therapeutic agent as it is readily absorbed and has been proposed to enter cells intact. The paramagnetic 2 H NMR technique has been utilized to follow the stability of this Cr(III) carboxylate assembly in biologically relevant media; its stability is consistent with the assembly being able to enter cells intact.

Paramagnetic 2H NMR is a viable technique to study the formation and degradation of trinuclear basic Cr(III) carboxylate assemblies in a variety of solvents. The stability of the nutritional supplement Cr3 in biologically relevant media is consistent with the complex being able to enter cells intact from the bloodstream.Figure optionsDownload as PowerPoint slide